Berlin 2012 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 4: Spin-dependent Transport Phenomena

MA 4.10: Vortrag

Montag, 26. März 2012, 12:00–12:15, H 1012

Mn_3−xGa based magnetic tunnel junctions with perpendicular magnetic anisotropy — •Manuel Glas, Daniel Ebke, Markus Schäfers, Patrick Thomas, and Günter Reiss — Thin Films and Physics of Nanostructures, Bielefeld University, Germany

The integration of Mn_3−xGa thin films with perpendicular magnetic anisotropy into magnetic tunnel junctions was investigated. MgO (001) and SrTiO₃ (001) substrates were used to achieve epitaxial (001)-oriented thin films. Crystallographic and magnetic measurements were performed to characterize the Mn_3−xGa electrodes. A strong Mn oxidation at the barrier interface was found from X-ray absorption spectroscopy (XAS). Therefore, a thin protection layer of CoFeB or Mg was deposited to improve the quality of the interface between barrier and electrode. A magnetically perpendicular counter electrode was formed by Co/Pt multilayers. Major loop hysteresis measurements suggest a magnetic decoupling between the electrodes through the MgO barrier. First transport measurements showed a maximum room temperature TMR ratio of 18 % for Mn_2.3Ga/CoFeB/MgO/CoFeB/{Co/Pt}₁₀ on MgO and 14 % on SrTiO₃ substrates. The corresponding low temperature (13 K) TMR values reach 32 % for MgO and 26 % for SrTiO₃ substrates. The obtained transport properties will be compared to Co/Pd based magnetic tunnel junctions with perpendicular magnetic anisotropy.